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ESTRO 35 2016 S7
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radiation oncology centers worldwide. We now know that
these side effects can most often be attributed to the use of
outdated RT techniques. As treatment techniques started to
improve, enabling to limit the dose to the organs at risk,
prospective trials were initiated to evaluate the contribution
of lymph node treatment to overall outcome for early stage
breast cancer patients. The results of several studies were
presented over the last couple of years. They demonstrate
that an increased disease-free survival rate following a
decrease of the risk of distant metastases can be obtained in
patients with risk factors, including those with involvement
of the axillary lymph nodes and those with a centrally or
medially located primary tumour. Moreover, a trend towards
an improved overall and (statistically significant for some of
the studies) breast cancer specific survival was
demonstrated. No increase was seen in the other causes of
death and, at a median follow-up of around 10 years, no
significant or clinical relevant increased toxicity was found,
apart from a slight increase in the risk for pulmonary toxicity.
The concept of “any recurrences”, introduced by the EBCTCG
in 2011, as important endpoint of the evaluation of the effect
of all types of treatments (including locoregional ones such as
surgery and RT) fits much better to the interpretation of the
recently presented results. In this era of earlier diagnosis and
more widespread use of adjuvant systemic treatments
leading to a 10-year overall survival exceeding 80%, clinically
detectable locoregional recurrences as a separate endpoint
might indeed be considered as less relevant. Firstly, the
patient will be affected heavily by any type of recurrence
and secondly because of the complex interaction between
the efficacy of systemic treatments with the influence of
loco-regional treatments on overall survival. By merely
focusing on locoregional control, we risk to neglect that once
distant metastases are found no further efforts are
undertaken
to
detect
locoregional
recurrences.
By
eliminating microscopically non-detectable cancer cells in
the lymph nodes with
RT, the risk of secondary metastasizing
of
those cells and thereby ultimately the overall risk of
recurrence of the
breast cancer will be reduced. This is in
line with the findings of the EORTC trial in which a trend was
seen towards more benefit for patients who where treated
with both hormonal treatment and chemotherapy and less
benefit for the small group of patients with 10 or more
involved axillary lymph nodes: patients with a better
prognosis (lower risk factors and/or better systemic therapy)
experience more benefit from locoregional treatments. With
modern RT techniques, the benefits of optimizing
locoregional control will likely not be counterbalanced by
side effects including late cardiovascular mortality.
Moreover, the new ESTRO guidelines for target volume
delineation clearly reduce the size of the target volumes
while simultaneously considering the regional lymph nodes
even more than before as a whole. We also expect that the
real benefit of loco-regional RT used to be diluted in the past
(including the recently presented trials) by suboptimal dose
coverage of the target volumes. Therefore, we expect that
with contemporary RT techniques and appropriate target
volume delineation, not only a significant reduction of the
dose to the organs at risk but also a much better coverage of
especially the internal mammary lymph nodes is achievable,
which is likely to result in a further improvement of the
benefit of locoregional RT for patients with early stage breast
cancer that have a risk for bearing microscopical tumor
deposits in the regional lymph nodes.
SP-0017
Technical approaches to regional lymph node irradiation
for breast cancer
A. Kirby
1
The Institute of Cancer Research and The Royal Marsden
NHS Foundation Trust, Radiation Oncology, London, United
Kingdom
1
The quality of radiotherapeutic approaches to treating
locoregional lymph nodes in breast cancer is improving. This
talk will review the latest evidence pertaining to each aspect
of the planning and treatment pathway in order to inform
best practice. Recently published atlases capable of
improving consistency in outlining target and non-target
volumes will be reviewed. Using data relating outcomes to
dosimetry, we will then review the evidence base for target
and non-target tissue dose constraints and objectives.
Different radiotherapeutic approaches including breath-hold,
volumetric-modulated arc therapy, and proton beam therapy
will be compared in terms of dosimetry and resource
implications. Potential efficiency savings in the treatment
pathway will also be discussed together with a review of the
possible impact of bluer-sky technologies.
Symposium: Assessment and management of rectal
morbidity
SP-0018
Towards a scoring system built on six distinct radiation-
induced illnesses producing late gastrointestinal effects
G. Steineck
1
Göteborg University, Department of Oncology- Institute of
Clinical Sciences, Göteborg, Sweden
1
, R. Jörnsten
2
, V. Skokic
1
, U. Wilderäng
1
, G.
Dunberger
1
2
Göteborg University, Chalmer's Technical Institute,
Göteborg, Sweden
As shown in randomized studies, radiotherapy has a critical
role when we cure prostate cancer by using multimodal
treatment strategies. We frequently use radiotherapy to cure
gynecological cancer. Both Intensity-Modulated Radiation
Therapy and Volumetric Modulated Arc Therapy have the
potential to drastically increase the ratio between
possibilities for cure and risk of late effects. Still, crude
measurements of patient-reported outcomes, as well as
factors that may modify the how radiation cause late effects,
compromise these possibilities. We lack details to provide
parameters from dose-volume modelling to utilize the full
potential of these new technologies. Concerning bowel
health, current scoring systems of radiation-induced late
gastrointestinal must be refined. Important socially
invalidating symptoms are not scored. An example is
unexpected defecation into clothing – not sensing the need to
go to the toilet and a sudden defecation into clothing as if
one were already on the toilet. We documented this
symptom among 11 percent of gynecological-cancer
survivors. Another example is frequent and uncontrolled
noisy flatulence. Traditional scoring systems have scales that
do not distinguish or clearly depict person-incidence (events
per individual per time unit), intensity and duration. But,
probably most important, as we learn that decreased bowel
health depends on several different types of radiation-
induced illness, we understand that grouping symptoms from
different illnesses together in a score compromises our ability
to acquire knowledge for prevention or relief. We cannot
disentangle these different radiation-induced illnesses when
symptoms from several illnesses are grouped together in the
data sets we retrieve. Clearly, new strategies are needed. In
my talk, I will propose a scoring system based on the data
indicating that the at least 28 radiotherapy-induced atomized
late gastrointestinal symptoms derive from six distinct
illnesses, that is, six sets of risk organs or mechanisms. We
have data from around 1500 survivors supporting this
position. As we accumulate data for each of these six
illnesses, we can define parameters in dose-volume models
built on patient-reported outcomes much better than we
previously could. Possibly we can also learn how, by
employing probiotics or dietary changes, we can influence
the interplay between the gut flora and stem-cell renewal to
counteract inflammatory processes that probably are
important for several of the six illnesses. Moreover, the
knowledge may stimulate development of mouse models in
which we can test, for example, how different bacterial
species influence radiation-induced inflammation in the
rectal wall. In the talk, I will give preliminary results from
the establishment of such a model. A simplified
nomenclature could label the six illnesses as involving
processes resulting in leakage-related symptoms, urgency-
related symptoms, constipation-related symptoms, symptoms